The CW is famous for doing a massive superhero crossover involving the Arrowverse shows for years now. This year’s effort is called “Elseworlds,” and focuses on mashing up characters from The Flash, Arrow, and Supergirl, with a few new and exciting faces (Batwoman and Lois Lane!) thrown in. Here’s a quick look at what to expect in Part 1:

“When Barry Allen and Oliver Queen wake up one morning and realize they have swapped bodies with each other, the two set off to find out what disturbed the timeline to cause such a shift. However, things quickly go from bad to worse when they present their case to Team Flash and the gang doesn’t believe them. Barry and Oliver realize they need Supergirl’s help and travel to Smallville on Earth-38 where they end up meeting Kara’s cousin, Clark Kent (Tyler Hoechlin), and intrepid reporter Lois Lane (Elizabeth Tulloch).”

During a recent visit to the set of Arrow, series star Stephen Amell opened up about the crossover and what he was most excited about.

Image via The CW

QUESTION: We know a lot about the crossover from your social media, so thanks for that.

STEPHEN AMELL: Now, by the way, I wasn’t going rogue. That was all designed based off of production schedule and the amount that we shot out on the street in the public. We always think that it’s better for us to show people before they see a grainy photograph. So, believe me when I tell you that was all by design.

QUESTION: We definitely know a lot more about the crossover than in previous years, so that’s exciting.

AMELL: Do you though? (Laughter)

QUESTION: What was it like for you to become The Flash, after all these years of just being the Green Arrow?

AMELL: Oh, it was the most, I don’t know if I’d call it the most rewarding, but it was the most fun that I’ve had, maybe ever, throughout the course of doing the show.

So much of it felt because Grant I had a discussion very early on. Grant [Gustin] and I saw each other at dinner last night, because the CW executives are up here for The Flash 100th episode party and the Supernatural 500th episode and it was weird because Grant and I, after spending every waking minute with each other for the better part of a month, we hadn’t seen each other for like 10 days. It was like, “How are you?” I had so much fun, but we had the discussion very early on that if this was gonna work that we really had to go for it, right?

Image via The CW

So, there are elements, because he has my learned abilities and his superpowers, there are elements of each other’s personality that each of us have to embrace in order to be successful at the mission that’s in front of us. So, every once in a while, I’m channeling my inner Barry Allen and I’m looking at Grant after the tape going, “Is it too much now?” We had a blast. I think that the crossover this year, even if we don’t have as many DC characters necessarily as we did last year, this feels like the first time, or at the very least, the best example of us just embracing the fun of it all and embracing all of the opportunities that we have because of all the things that we’ve had a chance to build over the years.

QUESTION: Can you tell us how you felt about Batwoman being introduced into the Arrowverse?

AMELL: Fantastic. It was great. You know, the idea that we get to go to Gotham City was really exciting, and we got to do something that I’d never done. I’ve never shot the show anywhere but Vancouver, so to go to Chicago and do all that, it felt amazing. Ruby (Rose/Batwoman) is fantastic. I think she’s gonna do great and you know, I’m all for expanding the universe, right? Every time. Always. There’s no scenario where I go, “No thank you.” I mean, I definitely got to shoot on sets in Gotham City, and Star City, and Central City, and Earth 38, and somewhere that I can’t even properly explain. I never thought that that would happen.

Part 1 of the “Elseworlds” crossover airs on Sunday, December 9th on the CW.